A dictionary that maps HTML5 named character references [1] to the
equivalent Unicode character(s), e.g. html5['gt;']=='>'.
Note that the trailing semicolon is included in the name (e.g. 'gt;'),
however some of the names are accepted by the standard even without the
semicolon: in this case the name is present with and without the ';'.
See also html.unescape().